<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>

</head>
<script>
    function canshu(a, b) {
//        如果有参数b就用b 如果没有就用默认的参数
        b=b||8;
        return a+b;
    }
    console.log(canshu(3));


//箭头函数的使用


    var show=(a,b)=>a+b;
    console.log(show(2,5))



</script>
<body>

</body>
</html>